Disentangling the effect of farming practice from aridity on crop stable isotope values: A present-day model from Morocco and its application to early farming sites in the eastern Mediterranean

Abstract

Agriculture has played a pivotal role in shaping landscapes, soils and vegetation. Developing a better understanding of early farming practices can contribute to wider questions regarding the long-term impact of farming and its nature in comparison with present-day traditional agrosystems. In this study we determine stable carbon and nitrogen isotope values of barley grains from a series of present-day traditionally managed farming plots in Morocco, capturing a range of annual rainfall and farming practices. This allows a framework to be developed to refine current isotopic approaches used to infer manuring intensity and crop water status in (semi-)arid regions. This method has been applied to charred crop remains from two early farming sites in the eastern Mediterranean: Abu Hureyra and 'Ain Ghazal. In this way, our study enhances knowledge of agricultural practice in the past, adding to understanding of how people have shaped and adapted to their environment over thousands of years.

What can crop stable isotopes ever do for us? An experimental perspective on using cereal carbon stable isotope values for reconstructing water availability in semi-arid and arid environments

“…Secondly, Δ 13 C variability can help assess the magnitude of variation in conditions between different fields near a site (provided it can be reasonably assumed that the crops were cultivated locally). If variation is significantly larger than "normal" intra-plot variation (< 0.5‰ in our study, comparable to the 0.5‰ observed by Wallace et al 2013), it is likely that the crops were grown under very different conditions to each other (Riehl et al 2014;Styring et al 2016).…”

“…In light of this, we suggest to limit the interpretation of Δ 13 C data to high and low values, while especially for wheat, intermediate values should be viewed with caution. Interpretation of the latter can be improved using a multi-proxy approach, such as by using weed functional characteristics in conjunction with stable isotope analysis (Bogaard et al 2016;Styring et al 2016Styring et al , 2017. Since many Δ 13 C values measured from archaeological samples fall in these intermediate ranges (Riehl et al 2014;Vaiglova et al 2014;Wallace et al 2015;Styring et al 2017), it is very important that this limitation is taken into account.…”

Strontium and nitrogen isotopic evidence of food import to Tell Ashara–Terqa, a Bronze Age city on the Euphrates, Syria

“…Although most individual EBA and MBA δ 15 N values were higher than 13‰, in a few cases, they were much lower, even as low as 9‰ (Figure ), which is near 8.17‰, the lowest value in the later subsample (Sołtysiak & Schutkowski, ). As nitrogen isotopic values are correlated not only with the level of manuring (Styring et al, ) but also with average annual precipitation (Pate & Anson, ) and animal protein consumption (Hedges & Reynard, ), these low‐δ 15 N outliers may potentially be evidence of (a) human migration from much more humid areas (e.g., dry farming zone, a few hundred kilometers north to Tell Ashara), (b) food import from more humid areas, (c) low level of manuring in a few local fields combined with individual rather than communal grain storage, and (d) individual diets with much lower amount of animal proteins. Although observed differences are too high to consider the fourth possibility as the main factor, as it would imply spacing of more than one trophic level (cf.…”

From Traditional Farming in Morocco to Early Urban Agroecology in Northern Mesopotamia: Combining Present-day Arable Weed Surveys and Crop Isotope Analysis to Reconstruct Past Agrosystems in (Semi-)arid Regions

“…The average measurement uncertainty for δ C air ) determined from air sampled at weekly intervals during the months that the crops were growing (White et al 2015), using the equation below. We have therefore used more up to date measurements of the δ 13 C value of atmospheric CO 2 than in Styring et al (2016), with the result that the modern Moroccan cereal Δ…”

“…The Δ (Table 4). Styring et al (2016) have developed a model incorporating eastern Mediterranean plant isotope surveys by Hartman and Danin (2010) to aridity per se from additional enrichment due to manuring, though more work is needed to groundtruth aridity effects in cereals.…”